On 02/27/2014 07:24 AM, Theodore Ts'o wrote: > On Thu, Feb 27, 2014 at 07:10:25AM -0800, H. Peter Anvin wrote: >> Keep in mind, too, that for the kernel we don't care about the full >> C standard but a subset. We rely on extrastandard behavior all over >> the place. For all ABIs supported by the kernel, sizeof(_Book) == 1 >> and so everything is sane. > > Do we have a fairly comprehensive list of what these extrastandard > requirements / assumptions are? It might be a good idea to have one > that we can point to, so that (a) people who are trying to define a > new architecture knows what they need to handle, (b) and so we can > give a list of things that static code analyzers like smatch and > coverity and sparse should be able to suppress (perhaps in a Linux > kernel-only mode). > No, but I think we can certainly make a list... a lot of it right now sits in various people's heads. Here are a couple: - Bytes are 8 bits - Signed integers will be 2's complement - sizeof char, short, int, long, and long long will be 1, 2, 4, 4, 8 or 1, 2, 4, 8, 8 on 32- and 64-bit processors, respectively. - sizeof(long) == sizeof(void *) - NULL is represented by all zero - Structures will not add padding as long as all the members are naturally aligned. Someone want to set up a collaborative document of some kind and collect more? -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-sparse" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
